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61.
In a steel tube mill where an endless stream of steel tube is supplied from a manufacturing facility, trim waste is never made regardless of cutting patterns used and the standard cutting stock problem seems meaningless. Therefore, the continuous stock cutting problem with setup is introduced to minimize the sum of cutting time and pattern changing time to meet the given demand. We propose a new configuration of cutting machines to achieve higher production efficiency, namely the open-ended configuration as opposed to the traditional closed-ended configuration, thereby two variants of the problem are defined. We propose linear formulations for both problems using binary expansion of the number of pieces of different types in a pattern. Furthermore, we define the time for pattern change as a linear function of the number of knives used in the pattern to be more realistic. Computational studies suggest that the open-ended cutting machine may improve the production time by up to 44% and that our linear formulations are more efficient than the existing ones. 相似文献
62.
Nguyen Quang VuDanielle Grée René GréeEric Brown Gilles Dujardin 《Tetrahedron letters》2003,44(34):6425-6428
Reaction of polysubstituted 2-hydroxyalkyldihydropyrans with DAST led regiospecifically to fluorination at the exocyclic position, except for primary alcohols. Difluorination of carbonylated analogues with deoxo-fluor™ occurred also regioselectively. The unexpected stability and synthetic potential of these new allylic fluorides are discussed. 相似文献
63.
P. Veeraraghavan Ramachandran Baoqing Gong Aleksandar V. Teodorovi? 《Journal of fluorine chemistry》2007,128(7):844-850
A comparative study of the asymmetric reduction of representative aryl and alkyl α-fluoro- and α-chloromethyl ketones using (−)-diisopinocampheylchloroborane [(−)-DIP-Chloride™] and (−)-B-isopinocampheyl-9-borabicyclo[3.3.1]nonane [R-Alpine-Borane®] has been made. It was observed that DIP-Chloride™ is superior in terms of the rate and enantioselectivity for both classes of halo-ketones. While the reduction of monofluoroacetone and trifluoroacetone with DIP-Chloride™ provided the product alcohols in 61% ee and 96% ee, respectively, the reduction of difluoroacetone yielded only 5% ee. The influence of a lone halogen atom was not observed for monochloroacetone, all of which point towards a chelating effect of monofluoroacetone on the Lewis acidic chloroborane. 相似文献
64.
基于小波分形理论的股价指数信息量测度研究 总被引:4,自引:0,他引:4
本把小波分析和分形理论引入到股价指数时间序列的分析中,给出了股价指数波动复杂性的信息量测度方法——信息熵和分形维方法。通过对上证综指和深证成指1994年1月3日至2002年3月4日期间的数据进行的实证分析显示,两种方法均能刻画股价指数波动的复杂程度,这对初步了解我国股市场的波动规律有一定的实际意义。 相似文献
65.
The sorption of copper(II) on a solid, iminodiacetic based, chelating material, the Empore™ membrane, in alcoholic solutions is considered. Determination of the acid-base properties, kinetic of metal sorption and complexing properties, in solutions with different percentages of ethanol, ranging from 0 to 40% is undertaken. The results are compared with those obtained using the classical iminodiacetic resin Chelex 100 in beads. No significant differences are found in the thermodynamic properties, but the kinetics of the metal sorption on the membrane is slower and a dependence of the process rate with the alcoholic content is observed. In the present investigation, the detection of copper(II) species both in alcoholic Italian distillate “grappa” and in its intermediate product (“flemma”), is carried out by the Resin Titration (RT) method using, as competitive reagent, the Empore™ membrane. To validate the procedure, synthetic solutions containing different percentages of ethanol are analysed. 相似文献
66.
Ashok Razdan 《Pramana》2002,58(3):537-544
In this paper we study Bombay stock exchange (BSE) index financial time series for fractal and multifractal behaviour. We
show that BSE index time series is monofractal and can be represented by a fractional Brownian motion. 相似文献
67.
Shib Sankar Sana 《Applied mathematics and computation》2011,218(7):3277-3288
The paper deals with an inventory model to determine the retailer’s optimal order quantity for similar products. It is assumed that the amount of display space is limited and the demand of the products depends on the display stock level where more stock of one product makes a negative impression of the another product. Besides it, the demand rate is also dependent on selling price and salesmen’s initiatives. Also, the replenishment rate depends on the level of stock of the items. The objective of the model is to maximize the profit function, including the effect of inflation and time value of money by Pontryagin’s Maximal Principles. The stability analysis of the concerned dynamical system has been done analytically. 相似文献
68.
Nergiz KasimbeyliTugba Sarac Refail Kasimbeyli 《Journal of Computational and Applied Mathematics》2011,235(16):4663-4674
This paper considers a one-dimensional cutting stock and assortment problem. One of the main difficulties in formulating and solving these kinds of problems is the use of the set of cutting patterns as a parameter set in the mathematical model. Since the total number of cutting patterns to be generated may be very huge, both the generation and the use of such a set lead to computational difficulties in solution process. The purpose of this paper is therefore to develop a mathematical model without the use of cutting patterns as model parameters. We propose a new, two-objective linear integer programming model in the form of simultaneous minimization of two contradicting objectives related to the total trim loss amount and the total number of different lengths of stock rolls to be maintained as inventory, in order to fulfill a given set of cutting orders. The model does not require pre-specification of cutting patterns. We suggest a special heuristic algorithm for solving the presented model. The superiority of both the mathematical model and the solution approach is demonstrated on test problems. 相似文献
69.
70.
《Stochastic Processes and their Applications》2019,129(9):3174-3206
A class of singular stochastic control problems whose value functions satisfy an invariance property was studied by Lasry and Lions (2000). They have shown that, within this class, any singular control problem is equivalent to the corresponding standard stochastic control problem. The equivalence is in the sense that their value functions are equal. In this work, we clarify their idea and extend their work to allow Lévy type noise. In addition, for the purpose of application, we apply our result to an optimal trade execution problem studied by Lasry and Lions (2007). 相似文献